Rotor Magnet Angle Design for Reluctance Torque
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Solution Overview
Problem
The two-layer arrangement structure in rotating electric machines experiences significant increases in counter electromotive voltage and decreases in reluctance torque due to the radially outward protruding shapes of magnet holes, particularly at higher rotation speeds.
Innovation Solution
The rotor design includes first-layer and second-layer magnet holes symmetrically formed with respect to the d-axis, with the first-layer magnet angle smaller than the second-layer magnet angle, optimizing the magnetic path widths and reducing magnetic saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If magnet holes are formed to protrude radially outward to cope with centrifugal force at high rotation speeds, then the rotor can withstand higher centrifugal forces, but counter electromotive voltage significantly increases and reluctance torque decreases
Solution Approach 1:
The patent applies different magnet angles to different layers: the first-layer magnet holes have a first magnet angle while the second-layer magnet holes have a second magnet angle that is smaller than the first. This local differentiation allows each layer to be optimized for its specific radial position, enabling the rotor to maintain high rotation speed capability while improving reluctance torque by reducing the adverse effect of radial protrusion on magnetic flux distribution
Solution Approach 2:
The patent introduces a new design dimension by differentiating magnet angles between two radial layers. Instead of using a uniform magnet hole design, the invention creates a two-layer arrangement where each layer has optimized magnet angles, effectively adding a radial dimension to the magnet angle parameter and resolving the contradiction between speed and torque
2Strength
If magnet holes protrude radially outward, then centrifugal force resistance improves, but counter electromotive voltage significantly increases
Solution Approach 1:
The patent applies different magnet angles to different layers: the first-layer magnet holes have a first magnet angle while the second-layer magnet holes have a second magnet angle that is smaller than the first. This local differentiation allows the outer layer to maintain structural strength for centrifugal force resistance while the inner layer's smaller angle reduces the increase in counter electromotive voltage
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances reluctance torque without significantly increasing counter electromotive voltage, allowing for improved performance and higher rotation speeds.
Implementation Method 1
a rotor for a rotating electric machine, the rotor including: a rotor core in which first-layer magnet holes are formed symmetrically with respect to a d-axis as viewed in an axial direction, and second-layer magnet holes are formed radially inside the first-layer magnet holes
Implementation Method 2
the rotor core includes a first section that is located radially outside the first-layer magnet holes and forms an outer circumferential surface of the rotor core, a second section that passes between the first-layer magnet holes and the second-layer magnet holes
Data Source
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AI summary
Disclosed is a rotor for a rotating electric machine, the rotor including: a rotor core; a first-layer permanent magnet that is disposed in a first-layer magnet hole; and a second-layer permanent magnet that is disposed in a second-layer magnet hole. When a magnet angle related to one magnet piece is defined as an angle formed by a reference line extending in a direction vertical to a d-axis from an intersection between the d-axis and an extending direction of a side surface of the one magnet piece in a main magnetic flux direction as viewed in an axial direction and the extending direction of the side surface, and a radially inner side of the reference line as viewed in the axial direction is defined a positive side of the magnet angle, a first magnet angle related to a first magnet piece that forms the first-layer permanent magnet and is on the d-axis or closest to the d-axis is smaller than a second magnet angle related to a second magnet piece that forms the second-layer permanent magnet and is on the d-axis or closest to the d-axis.